It is an almost universal practice for draftsmen and artists to perform their work on a sheet of paper or other medium such as a drafting film which is removeably attached to a flat board or table. With the use of modern drafting equipment it is important that the drafting medium be firmly attached to the drafting board in a fixed position so that it does not shift position during use, but is, at the same time, readily removeable from the drafting board. A number of different methods of attaching the drafting medium to the drafting board have been used and are well known in the prior art, but each such approach has presented certain distinct disadvantages.
One approach is the use of a tack or pin to hold each corner of the drafting medium to the drafting board by penetrating the drafting medium with the shaft of the pin and embedding the point of the pin in the drafting board. Over a period of time the holes produced in the drafting medium tend to enlarge, destroying the integrity of attachment of the medium to the board and allowing the position of the medium to shift, and eventually tearing through the drafting medium. In addition, the extension of the pin or tack above the surface of the drafting medium makes it difficult to move drafting instruments over the corners and edges of the drafting medium.
Another approach has utilized tape to slick the corners of the drafting medium to the drafting board, commonly by placing a strip of single sided adhesive tape over each corner of the medium and adhering the ends of the strip of tape to the board. This method eliminates some of the disadvantages of the use of tacks or pins, but introduces other disadvantages. The primary difficulties are the tendency of the tape to roll up with passage of drafting instruments over it, and the need to remove the strips of tape each time the drafting medium is moved. In a varient of this method, fully coated bilaterally adhesive tape or other adhesive compound is placed between the drafting medium and the drafting board. With the use of fully coated bilaterally adhesive tape difficulty often arises when the drafting medium is removed from the drafting board, such as tearing of the medium or removal of the tape from the drafting board along with the sheet of drafting medium. The use of an adhesive compound without a flat substrate tape often produces a lump of adhesive compound between the drafting medium and the drafting board, creating problems with the smooth passage of drafting instruments over the corners of the medium.
Thus, there remains a need in the drafting field for an approach to the attachment of drafting media to a drafting board or table which maintains a firm and secure adhesion without the disadvantages of the prior art.